May 2, 1997

By Jeffery Kahn, JBKahn@LBL.gov

Though it does not yet rival the public interest in UFOs, cosmology -- the
study of the origin, evolution, and structure of the universe -- increasingly
engages the public imagination. Aware of this phenomenon, the Smithsonian
Institution's National Air and Space Museum currently is contemplating adding a
new gallery devoted to this field of exploration.

Since its opening in 1976, the museum has become a favorite of visitors to the
nation's capital. Its most famous exhibits include the original 1903 Wright
Brothers' airplane, Charles Lindbergh's Spirit of St. Louis, the Apollo 11
command module from the first manned lunar landing mission, and rocks retrieved
from the moon.

Dave DeVorkin, the museum's curator for the history of astronomy, is
spearheading the proposal to extend the museum to include the human quest to
investigate and understand the cosmos. Berkeley Lab has a significant role in
this story, says DeVorkin.

At this stage, says DeVorkin, "I am collecting objects that are worthy of
permanent preservation in the national collection, objects that have played a
prominent role in the history of astronomy. They would be displayed in a
proposed new gallery (an extension to the museum) to be constructed here. This
gallery would explore cosmology back to the beginning of human curiosity. Its
working title is "`Explore the Universe.'"

If "Explore the Universe" is built, it would open to the public around the
year 2001. Half of the 5,000-square-foot gallery would be devoted to
contemporary cosmology.

In recent months, DeVorkin has contacted the Physics Division's George Smoot
and the Material Sciences Division's Paul Richards. Both Smoot and Richards
led scientific teams that made seminal discoveries about the early universe.
Both have provided instruments and apparatus that now have become part of the
Smithsonian's permanent national collection of historic objects.

The two scientists have made their mark studying the cosmic microwave
background, the remnant radiation from the Big Bang that suffuses space.

Smoot's most significant contribution is well known. On April 23, 1992 at an
American Physical Society meeting in Washington, D.C., he announced the
discovery of fossil relics from the primeval explosion that began the universe:
15- billion-year-old primordial seeds that grew into the galaxies and
superclusters of galaxies evident today.

The discovery was made through the use of exquisitely sensitive microwave
receivers created for NASA's Cosmic Background Explorer (COBE) satellite. The
receivers detected regions of space 100 million light years across and larger
with temperature differences of a hundred-thousandth of a degree. As Smoot
explained, "These small variations are the imprints of tiny ripples in the
fabric of space-time put there by the primeval explosion process. Over billions
of years, gravity magnified these ripples into galaxies, clusters of galaxies,
and the great voids of space."

DeVorkin chose two microwave receivers -- known as Differential Microwave
Radiometers -- to make a part of the Smithsonian's permanent collection. One
was the prototype for COBE

and the other, flown on a U2 aircraft in the 1970s, was used to discover that
the motion of our own galaxy through space exceeds one million miles per hour
(relative to the distant matter in the Universe).

Paul Richards led a group that, in the 1970s, performed balloon-borne
experiments that provided compelling evidence that the cosmic microwave
background radiation is a blackbody spectrum.

When something is hot, it emits electromagnetic radiation. For every
temperature, there is a unique and corresponding distribution of wavelengths
and frequencies known as the blackbody spectrum, even for something as hot as
the Big Bang.

Says Richards, "At a time when there was significant uncertainty, our data
showed that the early universe was a blackbody. It documented that the
universe was not a steady state (in which matter is continuously created and
formed into new galaxies.) Instead, this was the strongest possible evidence
for the Big Bang origin of the radiation."

Richards recalls that it was Nobel laureate Charles Townes who first involved
him in astrophysics. Townes was always interested in the big questions of the
day and was aware that the existing measurements of the spectrum of the
background radiation showed large deviations from a blackbody spectrum.

Says Richards, "I was a condensed matter physicist in the Inorganic Materials
Research Division at the Lab with an expertise in using infrared spectroscopy
to probe the properties of matter. Townes approached me to say that he believed
I had the best technology for measuring the temperature of higher frequency
cosmic microwave background. He guessed, correctly it turned out, that we
already had the building blocks to do this science."

Richards joined with two graduate students, John Woody and John Mather (later
chief scientist for COBE). By 1974, they had built an apparatus that consisted
of an antenna, spectrometer, and detector, all cooled by liquid helium to a
temperature below 3 Kelvin. Beginning in 1973, this balloon-borne apparatus
made a number of flights. For the next15 years -- up until the time of COBE --
the results of these flights provided the best evidence available that the
background radiation indeed was a blackbody.

DeVorkin reports that elements of what came to be known as the Woody/Richards
experiment now have joined the Smithsonian's permanent collection.

Says DeVorkin, "It's too early to say whether we will receive approval from
the Smithsonian's director to create the `Explore the Universe' gallery. If we
receive the go-ahead, then we still must secure funding to build it. However,
even if the new gallery is not built, these objects will remain part of the
national collection and will be available for future exhibit both here and for
loan to other museums."